The Tamil Nadu government has prepared a ₹4,446-crore project for permanent flood mitigation measures for Chennai and has sought Central funds to take up the work.
Chennai is inundated almost every year during the northeast monsoon period. The only way out of the situation is construction of integrated stormwater drainage network.
CM’s plea
Tamil Nadu Chief Minister Edapaddi K Palaniswami submitted a memorandum to Pime Minister Narendra Modi in Delhi on Monday and requested him to instruct various ministries to allocate the necessary funds to take up work on the drainage network in Kovalam and Kosasthalaiyar Basin and to restore waterbodies.
Funds are also required for purchase of machinery as the Centre’s share. The Greater Chennai city and its urban neighbourhood spread over the river basins of Kosasthalaiyar, Cooum, Adyar and Kovalam are connected through the Buckingham Canal that is formed parallel to the coast in the tidal flats.
This system also functions as a unique system for draining surface run-off from the isolated watersheds sandwiched in the above four basins through the river mouths — Ennore Creek, Cooum river mouth, Adyar river mouth and Kovalam creek.
In addition to this, many macro drains such as Madhavaram- Manali Lake Canal, Old Napalayam Canal (North Chennai), Secretariat Canal, Semmencheri Canal (South Chennai), various tanks surplus courses like Kadapakkam lake surplus present in Greater Chennai Corporation will be treated holistically to mitigate the risks.
Flat terrain
The Greater Chennai and its peri-urban areas area spread over an almost flat terrain along the coastal plains having an average altitude of only 2 m above the sea level. The entire surface run off drains into the Bay of Bengal only through the outlets - Ennore creek in the north, Cooum and Adyar river mouths in the centre and Kovalam creek in the south.
The drainage network behind the above outlets formed with natural flood bowls like Ennore backwaters, Pallikaranai marshland and Muttukadu backwaters spread over tidal flats and vast areas of flood plains along the natural rivers, are no longer able to render their functions due to the changes in the land use induced by rapid urbanisation and industrial needs resulting in inundation in the upstream areas.